The Port Authority yesterday scrapped its helicopter fleet to save an estimated $3.7 million, canning three civilian pilots after deeming the unit an unnecessary financial burden, sources said.

The cut spells the end for the Airborne Services Unit, a PA staple since 1951.

It will result in discontinuation of aerial patrols of PA facilities by the two Sikorsky helicopters the agency now expects to sell for an estimated $8.5 million.

The three pilots, who each earns about $89,000 yearly, were informed they would be losing their jobs at the end of the month and get six months’ severance, sources said.

About half a dozen other support-staff workers — all of whom have union status — will be reassigned, the PA said.

“It’s surprising. The WTC was attacked twice, and they’re getting rid of us,” said one support-staff employee.

Paul Nunziato, president of the PA’s Police Benevolent Association, blasted the agency for treating “security issues like a riverboat gambler: No risk is too high if a few dollars can be saved.”